3-D structures of moving volcanic clouds to aid forecasts

3-D structures of moving volcanic clouds to aid forecasts

A research team from NASA's Goddard Space Flight Center in Greenbelt, Maryland has used the satellite measurements of sulfur dioxide, the main component of volcanic emissions, and maps of the location and vertical profiles of volcanic aerosols to improve the quality of movement forecast of volcanic clouds, following the volcano eruption. The study could help reduce the numbers of flights sidelined by volcanic eruptions, airline cancellations, and reroute costs.

A volcano eruption frequently sends a thick cloud of ash across the widespread area which strongly impacts the safety of the aviation. Ashes melting within an operating aircraft engine can also result in an engine failure which can be extremely dangerous or fatal. In the cases of ash emission, airlines usually consult the local weather agencies to determine the flight safety which is mostly manually estimated from the information of the Volcanic Ash Advisory Centers.

A volcanic cloud consists of the sulfuric acid droplets that get converted from the sulfur dioxide and silicate volcanic ash. For aviation, volcanic ash is potentially most deadly and it can be observed by the satellites from the scattering of ultraviolet light from the Sun.

While measurements of aerosol absorption in ultraviolet do not differentiate between the smoke, dust and ash aerosols, only volcanic clouds contain significant abundances of SO2, so satellite measurements of SO2 are especially valuable for unambiguous identification of volcanic clouds.

Knowing both the physical location and the altitude distribution of aerosols in the volcanic cloud allow more accurate forecasts in the days, weeks and months after an eruption. 

Video credit: NASA Goddard

“The capability of mapping the full extent of a three-dimensional structure of a moving volcanic cloud has never been done before,” said Nickolay A. Krotkov, a physical research scientist with the Atmospheric Chemistry and Dynamics Laboratory at NASA Goddard.

Researchers are currently making these measurements using the Limb Profiler instrument, part of Ozone Mapping Profiler Suite (OMPS) instrument, currently flying on the joint NASA/NOAA/DoD Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, launched in October 2011.

OMPS consists of a nadir mapper in charge for mapping ozone, sulfur dioxide and aerosols, a nadir profiler that measures the vertical distribution of ozone in the stratosphere, and a limb profiler that measures aerosols in the upper troposphere, stratosphere, and mesosphere with high vertical resolution.

“With the OMPS instrument, the volcanic cloud is mapped as Suomi NPP flies directly overhead and then as it looks back, it observes three vertical slices of the cloud,” said Eric Hughes, a research assistant at the University of Maryland.

In order to correctly forecast the direction of the ash plume, the height of the plume is particularly important, as a few kilometers of height can significantly contribute to predicting the plume movement.

Video credit: NASA

“Sulfate aerosols formed after large volcanic eruptions affect the radiation balance and can linger in the stratosphere for a couple of years,” said Krotkov. 

There have been large volcanic eruptions that have contributed to short-term cooling of Earth from the sulfur dioxide that reached the stratosphere. An example of such occurrence is the Philippines Mount Pinatubo eruption in June 1991. The scientists are studying the impacts of deliberately injecting sulfur dioxide into the stratosphere to contract the effects of global warming, known as climate intervention. 

“Nature gives us these volcanic perturbations and then we can see the impact on climate. These are the short- and long-term consequences of volcanic eruptions that have both aviation and climate applications,” concluded Krotkov.

Featured image credit: NASA Goddard

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